This is the bracket that goes with the acetal nut. It's just a piece of 50mm x 50mm x 10mm aluminum, squared up on the mill, slotted with a 6mm end-mill, drilled in the center with same, increased out to 16mm with a 16mm roughing endmill, and then bored out to ~21mm with the boring tool.
The finished piece. I just love the finish the boring tool puts on holes. The final pass was cutting ~0.1mm deep, feeding at about 0.03mm per turn, so it was taking a pretty fine cut indeed. The result is this mirror smooth finish. Total overkill for this piece, but I take any opportunity to practise. The results I'm getting these days are far improved over the mess I made with it when I first got it.
Acetal nut fitted to bracket. The bolts are just my usual M6 stainless steel. There's about 5mm of adjustment available in both the X and Y directions.
The driving side. The nut isn't actually totally flat on this side. It turns out the parting tool I used to cut it off the bar isn't totally straight, so there's ~0.07mm of curvature across the nut. Which turned out to be fine as it's the otherside that fits to the bracket, but it's still annoying. Will have to get out the dial indicator and straighten the parting tool at some point; Come to think of it, I'd better do it soon before I forget and attempt to use a bent parting tool to part steel....
This bracket is fitted to the table mill and working very well. Much better than the old nut. Unsuprisingly, having the threaded hole accurate makes a big difference to the effort required to drive it. The tiny steppers I have easily drive it at better than 1200 rpm now.